The present invention relates to alkaline electrochemical cells. In particular, the present invention relates to active compositions for electrodes of alkaline electrochemical cells.
Rechargeable electrochemical cells may be classified as xe2x80x9cnonaqueousxe2x80x9d cells or xe2x80x9caqueousxe2x80x9d cells. An example of a nonaqueous electrochemical cell is a lithium-ion cell which uses intercalation compounds for both anode and cathode, and a liquid organic based or polymer electrolyte. Aqueous electrochemical cells may be classified as either xe2x80x9cacidicxe2x80x9d or xe2x80x9calkalinexe2x80x9d. An example of an acidic electrochemical cell is a lead-acid cell which uses sulfuric acid as the electrolyte, lead dioxide as the active material of the positive electrode, and metallic lead, in a high-surface area porous structure, as the negative active material.
Examples of alkaline electrochemical cells are xe2x80x9cnickel-basedxe2x80x9d alkaline cells. These cells use an alkaline electrolyte (such a potassium hydroxide) and nickel hydroxide as the active material for the positive electrode. Nickel hydroxide has been used for years as an active material for the positive electrode of alkaline batteries. The reactions that take place at the positive electrode of a nickel-based rechargeable electrochemical cell are reversible and include the following chemical reaction: 
At the positive electrode, Ni(OH)2 is oxidized to NiOOH during the charge operation. During discharge, the NiOOH is reduced to Ni(OH)2. Examples of such nickel-based alkaline batteries include nickel-metal hydride cells (Nixe2x80x94MH), nickel cadmium cells (Nixe2x80x94Cd), and nickel-zinc cells (Nixe2x80x94Zn). Nixe2x80x94MH cells used negative electrode using a hydrogen storage alloy as the active material. The hydrogen storage alloy is capable of reversible electrochemical storage of hydrogen.
In general, Nixe2x80x94MH cells utilize a negative electrode that is capable of reversible electrochemical storage of hydrogen, and a positive electrode of nickel hydroxide material. The negative and positive electrodes are spaced part in the alkaline electrolyte.
Upon application of an electrical potential across a Nixe2x80x94MH cell, the hydrogen storage alloy of the negative electrode is charged by the electrochemical discharge of hydrogen and the electrochemical generation of hydroxyl ions: 
The negative electrode reactions are reversible. Upon discharge, the stored hydrogen is released to form a water molecule and release an electron. (In a Nixe2x80x94Cd cell, cadmium metal is the active material in the negative electrode).
The active electrode material for both the positive and negative electrodes is usually affixed to a conductive substrate to form the positive and negative battery electrodes. One way to affix the active material to the conductive substrates is to first make the active materials into a paste by adding a small amount of binder and then applying this paste to the substrate. The present invention is directed to a new active material composition including a binder comprising a monosaccharide, a disaccharide, a pectin or a molasses. Electrodes incorporating this active composition have improved electrochemical and mechanical properties.
An object of the present invention is an electrode and an electrochemical cell having increased power. Another object of the present invention is an electrode and electrochemical cell having ripioved cycle life.
These and other objects of the invention are satisfied by an active composition for an electrode of an alkaline electrochemical cell, comprising: an active electrode material; and a binder comprising a monosaccharide, a disaccharide, a pectin or a molasses.
These and other objects of the invention are also satisfied by an electrode for an alkaline electrochemical cell, comprising: an active composition including: an active electrode material; and a binder comprising a monosaccharide, a disaccharide, a pectin or a molasses.
These and other objects of the invention are also satisfied by an alkaline electrochemical cell, comprising: at least one positive electrode; at least one negative electrode; and an alkaline electrolyte, the positive electrode and/or the negative electrode having an active material composition including a binder comprising a monosaccharide, a disaccharide, a pectin or a molasses.